Input on what helix to put in a 2008 m8

[fersch69]

I have a 2008 m8 with a speed werx y pipe and a mbrp can and a speed werx 4' air horn and also a speedwerx clutch kit(weights and green spring).I want to change the helix but not sure what the best one would be.I run anywhere from 3,000 - 8,000 elevation.If any one out there has some input that would awsome.Thanks.

 

[mountianguy]

Rkt or cutlers both work good